SE539744C2 - Apparatus for performing peritoneal ultrafiltration - Google Patents

Abstract

23 ABSTRACT An apparatus for ultrafiltration of a patient being overhydrated due to congestiveheart failure. The apparatus comprises a dilution syringe (16, 57) for removal of a portion ofperitoneal fluid from the peritoneal caVity. A glucose bag (25, 71) comprises glucoseconcentrate at a concentration of 30%. A small amount of glucose concentrate is mixed Withthe dilution fluid in the dilution syringe in order to dilute the glucose concentrate to below 3%concentration. Then, the mixture is filled into the peritoneal caVity from the dilution syringein order to replenish the glucose in the peritoneal caVity for maintaining a substantiallyconstant glucose concentration in the peritoneal caVity. In addition, peritoneal fluid isinterrnittently removed from the peritoneal caVity for counteracting increased intraperitonealfluid Volume and increased intraperitoneal pressure due to ultrafiltration. A UF bag (24, 55) isarranged for receiving such surplus peritoneal fluid. A glucose syringe (59) may be arranged for metering the glucose concentrate. (Fig. 1 is to be published With the abstract)

Description

TITLE: APPARATUS FOR PERFORMING PERITONEAL ULTRAFILTRATION FIELD OF INVENTIONThe present invention relates to a manual apparatus for performing peritoneal ultrafiltration of a patient in need thereof, for example due to congestive heart failure.

BACKGROUND Diuretic-resistant congestive heart failure is a problem of growing significance. It isrelated closely to the cardio-renal syndrome, which is characterized by chronic abnorrnalitiesin cardiac function, causing impaired renal function and progressive chronic kidney disease.

Congestive Heart Failure patients can benefit from fluid removal by ultrafiltration.These patients norrnally have functional kidneys, but suffer from fluid overload. The kidneysof these patients are generally healthy but are not fully functioning due to the failing heartwith increased venous blood pressure and sometimes low arterial blood pressure. Because thekidneys are not fully functioning, fluids build up in the patient and the fluid overloadcontributes to stress on the already partly failing heart.

The proper control of sodium and water balance is of vital importance because up to80% of hospitalizations from Congestive Heart Failure are due to acute over hydration andonly 5% are due to low cardiac output.

The patent document US7l35008B2 discloses a method and apparatus for theextracorporeal treatment of blood by utilizing a dual lumen catheter assembly peripherallyinserted in the blood vessels for the continuous removal and retum of blood for renalreplacement treatment, in particularly, treatment of congestive heart failure and fluid overloadby ultrafiltration. A catheter is inserted in a peripheral vein and maneuvered upward throughthe vascular system to access the reservoir of blood in the large or great veins for continuousblood withdrawal and treatment. Air-tight connectors are incorporated in the catheterassembly to overcome the untoward effects of negative pressure in blood withdrawal.

However, ultrafiltration via extracorporeal treatment of blood, results in risksassociated with access to the vascular system. In addition, the ultrafiltration may be excessiveresulting in hypotension.

A promising ultrafiltration method which do not use extracorporeal blood treatmentis used in peritoneal dialysis, in which the endogenous peritoneal membrane is used forultraf1ltration. A peritoneal ultraf1ltration fluid is instilled in the peritoneal cavity. The fluidcomprises an osmotic agent, such as glucose or Icodextrin or others, causing ultrafiltration.

Peritoneal ultraf1ltration is more gentle to the patient and seldom results in hypotension. In addition, peritoneal ultraf1ltration may be used daily outside the hospital without or withlimited need for medically trained professionals.

With the present PD regiments, such as CAPD, glucose based fluids are replacedevery two to four hours and has optimal ultrafiltration for only 2 to 3 hours or less. Eachreplacement may take up to one hour and increases the risk of infection. This reduces thefreedom and quality of life for the patients.

In addition, the use of glucose may result in the absorption of glucose into thecirculation, which may lead to hyperglycemia, hyperinsulinemia, and obesity. Icodextrin maycause other problems.

Addition of an osmotic agent to the peritoneal cavity may be detrimental to theperitoneal membrane if the concentration of the osmotic agent is excessive. Thus, theperitoneal membrane needs to be protected from local high concentration of osmotic agent,such as glucose, especially at the introduction site of the peritoneal cavity.

A peritoneal dialysis apparatus is disclosed in patent document WO2013109922A1.The document discloses a dialysis system comprising: a sorbent cartridge in fluidcommunication with at least one of a patient or a dialyzer, the sorbent cartridge including ahousing having a zirconium phosphate layer followed by at least one of a urease layer, azirconium oxide layer, or a carbon layer; a storage container in fluid communication with thesorbent cartridge; a pump in fluid communication sorbent cartridge and the storage container;and a control unit in operable communication with the pump, wherein the control unit isprogrammed to cause the pump to pump a dialysis fluid to flow (i) in a first direction throughthe sorbent cartridge, wherein the zirconium phosphate layer is contacted by the dialysis fluidbefore the at least one of the urease layer, zirconium oxide layer or carbon layer and (ii) in asecond direction, reverse from the first direction, through the sorbent cartridge wherein the atleast one of the urease layer, zirconium oxide layer or carbon layer is contacted by the dialysisfluid before the zirconium phosphate layer. The dialysis system, when used for peritonealdialysis, removes all peritoneal fluid in the peritoneal cavity, and pass the fluid through anadsorption cartridge into a receptacle, in which glucose (and other substances) may bereplenished, whereupon the peritoneal fluid is retumed to the peritoneal cavity, see Fig. 19.Removal of all dialysis fluid takes time, which decreases the effective treatment timecorrespondingly.

Thus, there is a need for an apparatus for providing a peritoneal fluid to theperitoneal cavity, which is optimized with regard to peritoneal ultraf1ltration of patients withheart failure.

The patients having need for peritoneal ultrafiltration may need an apparatus forperforming the ultrafiltration method, which is transportable and may be carried by thepatient, so that the patient is not tied to any stationary equipment. Furthermore, the apparatus should be simple to use.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to mitigate, alleviate or eliminateone or more of the above-identified deficiencies and disadvantages singly or in anycombination.

In an aspect, there is provided an apparatus for ultrafiltration of a patient in needthereof, for example a patient being overhydrated due to congestive heart failure. Theapparatus comprises: a patient line comprising a patient connector for connection to aperitoneal catheter connector for access to a peritoneal cavity of the patient; a dilutionreceptacle connected to the patient line for removal and retum of peritoneal fluid to and fromthe peritoneal cavity; a glucose receptacle comprising glucose concentrate to be mixed Withthe contents of the dilution receptacle and subsequent introduction of the mixture into theperitoneal cavity; Whereby glucose is replenished interrnittently for keeping a concentration ofglucose substantially constant in the peritoneal cavity.

According to an embodiment, the dilution receptacle may be a syringe having aretractable piston and a syringe stem for operation of the piston. The apparatus may furthercomprise a UF receptacle; a first valve and a second valve; Wherein the first valve may bearranged for connection of the syringe With said patient tube in a first position, and forconnection of the syringe With the second valve in a second position; the second valve may bearranged for connection of the first valve to the UF receptacle in a first position, and forconnection of the first valve to the glucose receptacle in a second position. The glucosereceptacle and the UF receptacle may be arranged as syringes each comprising a syringe stemattached to a corresponding piston and a nut arranged moveable along the syringe stem forlimiting the movements of the pistons inside each syringe.

According to another embodiment, the dilution receptacle may be a first syringehaving a piston and a syringe stem for operation of the piston, and Wherein the apparatusfurther comprises a second syringe having a retractable piston and a syringe stem foroperation of the piston, and Wherein the glucose bag comprises an enclosure having a constantvolume, and a partition Wall dividing the enclosure into tWo compartments, a first of Whichcomprising glucose concentrate and a second of Which comprising peritoneal fluid, andWherein introduction of peritoneal fluid inside the second compartment displaces an equalvolume of glucose concentrate out of the first compartment.

According to a further embodiment, the dilution receptacle may comprise a dilutionsyringe having a piston operated by a syringe stem and being connected to the patient line;and further comprising an ultrafiltration syringe having a piston and a syringe stem and beingconnected to the patient line via a one-Way valve and further being connected to acombination bag via a second one-Way valve, Wherein said combination bag comprises a first compartment for ultrafiltration fluid and a second compartment comprising glucose concentrate, whereby inflow of ultrafiltration fluid in said first compartment results in anoutflow of glucose concentrate, wherein the ratio between inflow and outflow is constant and larger than one, for example 5:1.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects, features and advantages of the invention will become apparent fromthe following detailed description of embodiments of the invention with reference to thedrawings, in which: Fig. 1 is a schematic diagram of a first embodiment of an apparatus for providing anultrafiltration fluid to a patient.

Fig. 2 is a schematic diagram of the first embodiment according to Fig. 1, including afill bag feature.

Fig. 3 is a schematic diagram of the first embodiment according to Fig. 1, including afurther feature.

Eig. 4 is a schematic diagram of a second embodiment of an apparatus for providingan ultrafiltration fluid to a patient, comprising a dilution syringe and a glucose syringe.

Fig. 5 is a schematic diagram of a third embodiment of an apparatus for providing anultrafiltration fluid to a patient, comprising a dilution syringe and a UF syringe.

Fig. 6 is a schematic diagram of a fourth embodiment of an apparatus for providingan ultrafiltration fluid to a patient.

Fig. 7 is a schematic diagram of a fifth embodiment of an apparatus for providing anultrafiltration fluid to a patient, comprising a dilution syringe and a UF syringe and a glucosesyringe.

Fig. 8 is a schematic diagram of the fourth embodiment according to Fig. 6 adapted to a patient having a double lumen catheter.

DETAILED DESCRIPTION OF EMBODIMENTS Below, several embodiments of the invention will be described. These embodimentsare described in illustrating purpose in order to enable a skilled person to carry out theinvention and to disclose the best mode. However, such embodiments do not limit the scopeof the invention. Moreover, certain combinations of features are shown and discussed.However, other combinations of the different features are possible within the scope of theinvention.

An apparatus for performing a peritoneal ultrafiltration method may in principle beconstructed similar to an apparatus for performing peritoneal dialysis. However, differentoptimizations are due since these two apparatuses perform different medical treatments.

It is noted that an apparatus for performing peritoneal dialysis is simultaneously arranged for performing peritoneal ultrafiltration. However, the task to remove unwanted products, such as urea and creatinine, is norrnally the focus. Thus, a peritoneal dialysisapparatus is norrnally arranged for removing such unWanted products, for example byadsorption, or by dialysis, While the glucose concentration is norrnally of less importance. Seefor example the patent document WO20l3 l09922Al, mentioned above. Thus, theultrafiltration may become less than optimal.

On the other hand, a peritoneal ultrafiltration apparatus is optimized for providingultrafiltration Without overloading the patient With glucose, While removal of unWantedproducts (such as urea) is of second importance. In addition, a gentle ultrafiltration is desiredin order to avoid complications for overhydrated congestive heart failure patients.

The peritoneal dialysis/ultrafiltration method is preferred over hemodialysis, sincethe patient is free from hospitalization and can perform the peritoneal dialysis/ultrafiltrationmethod at home or at any place. In addition, the peritoneal dialysis/ultrafiltration method canbe performed more often, for example l0 to 16 hours daily during daytime or 8 to 12 hoursduring nighttime.

The present embodiments of the dialysis ultraf1ltration apparatus and methodaccording to the invention is constructed having the following precautions in mind: l) Use of heavy mechanical devices such as pumps driven by electric batteriesshould be avoided or minimized. The patient should be able to carry the apparatus all thetreatment time. 2) The method should be able to be performed With only human forces by the patienthimself. 3) For optimizing ultrafiltration and minimizing body absorption of glucose, a lowand substantially constant concentration of glucose should be used. 4) High intraperitoneal pressure should be avoided. 5) Exposure of the entrance area of the peritoneal cavity from high glucoseconcentration should be avoided.

The peritoneal dialysis method most frequently used today is CAPD. During thismethod, a high volume of peritoneal dialysis fluid is instilled in the peritoneal cavity, forexample four times per day. The peritoneal dialysis fluid is maintained in the peritoneal cavityduring for example 2 hours to 3.5 hours. Then, the peritoneal fluid is removed and discardedand fresh dialysis fluid is instilled, Which norrnally takes about 30 minutes or more. Thevolume of peritoneal fluid instilled each time is norrnally 2000 ml or 2400 ml or as much asthe patient can take. If an ultraf1ltration of 400 ml per exchange should be obtained, thevolume removed Will be 400 ml larger.

The use of such high volumes results in a relatively high pressure in the peritonealcavity. Such high pressure Will counteract ultrafiltration. In order to reduce the intraperitonealpressure, it may be advantageous to remove some fluid more often than each third or fourth hour.

CAPD uses different glucose concentrations in dependence of the need of a patient.The glucose concentrations norrnally range from l.5% to 4.25%. However, several reportshave indicated that high glucose concentrations may result in compromised peritonealfunction, at least during long time exposure. Thus, the present embodiments use a maximumglucose concentration of 3.0%.

In CAPD a high initial glucose concentration is used and is not altered during thedwell time. Glucose may have a halftime of about 60 to 120 minutes, resulting in a 50%reduction of the concentration during such halftime. Thus, at least about 75% of the glucosecontents may be absorbed during a CAPD dwell, resulting in absorption of about 65 gramglucose per dwell for 4.25% for the highest concentration of glucose in 2 liter solution and upto 22 gram glucose for l.5%. However, CAPD with l.5% glucose results in a smallultrafiltration.

Fluid inside the peritoneal cavity is absorbed via lymphatic reabsorption and otherroutes which may be about 1 to 2 ml/min. Thus, if the glucose concentration is reduced tobelow a specific concentration, ultrafiltration previously obtained is removed and no netultrafiltration is obtained. Such specific glucose concentration when ultrafiltration is balancedby lymphatic reabsorption may be in the range of 0.5% to 1.0%.

The inventors have found that if a substantially constant glucose concentration isarranged in the peritoneal cavity, a relatively low maximum concentration of glucose can beused. In addition, a high initial ultrafiltration is not beneficial but a small but persistentultrafiltration will do better. Thus, a low glucose concentration and a low intraperitonealpressure are desired.

For a specific patient to be discussed below, in which 1500 ml peritoneal fluid ofl.0% glucose concentration had been instilled, it has been deterrnined that the glucoseremoval rate at l.0% glucose concentration was about 0.1 mg/min and the net ultrafiltrationwas about 3 ml/min. During the course of time, the glucose concentration decreases and wasabout 0.71% after 30 minutes and the net ultrafiltration was 1.5 ml/min. After another 30minutes, the glucose concentration was 0.5% and the net ultrafiltration was zero, which meansthat the osmotic ultrafiltration due to glucose was balanced by lymphatic reabsorption ofwater. If the instilled volume was higher, the lymphatic reabsorption was also higher, due to ahigher intraperitoneal pressure.

In order to maintain the concentration above 0.71%, it was desired to replenish 4.35gram of glucose per 30 minutes in order to restore the concentration to 1.0%. In order tomaintain the lymphatic reabsorption sufficiently below the osmotic ultrafiltration, a removalof about 60 ml fluid per 30 minutes was desired in order to keep the intraperitoneal pressuresufficiently low.

The apparatus according to embodiments should be constructed so that it can be carried by the patient during a daily treatment time of 10 hours. Thus, it is essential that the Weight of the apparatus including fluids will be as small as possible. If 3% glucoseconcentration fluid is used, which is considered to be safe for introduction into the peritonealcavity, more than 3 liters of fluid would be required per 10 hours treatrnent. Thus, a glucosereplenishment solution having a higher concentration of glucose is desired, such as 10% (900ml) or 30% (300 ml).

Fluid having 30% glucose concentration should not be infused directly into theperitoneal cavity, since such infusion may result in tissue damages and compromisedfunction, at least during long term exposure.

In order to dilute the high concentration glucose solution, some fluid is removedfrom the peritoneal cavity in order to dilute the glucose concentrate. If 4.35 g of glucoseshould be entered, 176 ml of peritoneal fluid (having a concentration of about 0.7%) would berequired for diluting 14.5 ml of 30% glucose concentrate to a final concentration of about 3%(l90.5 ml). Below, this will be rounded to 15 ml and 4.5 g glucose and 175 ml of dilutionfluid. Such replenishment is made with 30 minutes intervals.

The above mentioned data was given for a specific patient in order to elucidate theembodiments below. However, such data may vary over time for the specific patient. Inaddition, each patient has his own characteristic data. Thus, glucose infusion rate and UF fluidremoval rate may be adjusted to the specific person and may be adjusted over time. There areseveral theoretic works describing the transport kinetics, for example by a three-pore-model.

A first embodiment of an apparatus for performing the above glucose infusion andfluid removal is disclosed in Fig. 1.

A peritoneal cavity of a patient is shown schematically at 1. A peritoneal catheter 2 isarranged for communicating fluid into and out of the peritoneal cavity. The peritoneal catheter2 ends in a connector 3, which is arranged to be connected to a patient connector 11 of theultrafiltration apparatus 10, preferably by an aseptic method norrnally used in for exampleCAPD or APD.

The apparatus 10 further comprises a patient tube 12, at one end connected to saidconnector 11 and at the other end connected to a first inlet/outlet 13 of a first two-way valve29. A second inlet/outlet 14 of the first valve 29 is connected to a syringe 16 having a syringestem 17 for controlling the volume inside the syringe by moving a piston 41 inside thesyringe. In the position of the first valve 29 shown by solid lines, the syringe 16 maywithdraw peritoneal fluid from the peritoneal cavity of the patient by exerting a pulling actionon syringe stem 17 as shown by arrow 18. The syringe 16 may have a volume of about 250 mlor slightly larger.

A second two-way valve 20 is connected to a third inlet/outlet 15 of the first valve 29via a first inlet/outlet 21 of the second valve 20. A second inlet/outlet 22 of the second valve20 is connected to a large syringe 24 having a volume of about 1500 ml, which corresponds to a desired total ultrafiltration volume of 1200 ml over 10 hours plus the volume of infused glucose solution, 300 ml. A third inlet/outlet 23 of the second valve 20 is connected to a thirdsyringe 25 having a volume of 300 ml and comprising glucose concentrate at a concentrationof 30%, thus initially comprising 90 gram of glucose. The pistons of the second and thirdsyringes may be used for indicating the filling level of the syringe by means of gradings 31,32, which are graded in 20 half-hours.

A replenishment cycle is as follows: Initially, the first valve 29 is arranged in theposition shown by solid lines in Fig. 1 where after the piston rod 17 is pulled as shown byarrow 18 in order to fill the first syringe 16 with peritoneal fluid taken from the peritonealcavity. About 250 ml is removed, resulting in that the syringe is full. Then, the first valve 29is switched to an altemate position shown by broken lines in Fig. 1 and the piston rod 17 ispushed in the other direction as shown by arrow 19 in order to pass fluid from the first syringe16 into an upper compartment 26 of the ultrafiltration syringe 24. The piston rod 17 isoperated until 75 ml of fluid has been entered into compartment 26 of syringe 24 and 175 mlof fluid is left in the syringe 16. The syringe may be provided with a grading or scale 27,which indicates the positions. There may altematively be a shoulder which indicates when 75ml has been removed from the syringe.

Then, the second valve 20 is moved to an altemate position shown by broken lines inFig. 1, whereupon the piston rod 17 is pulled according to arrow 18 until 15 ml of glucoseconcentrate has entered the first syringe 16, resulting in 190 ml of fluid in the first syringe 16.The glucose concentrate will mix with the contents of the first syringe, which totally is about190 ml of fluid, whereby the glucose is diluted to a concentration below 3%. There may begradings or altematively a shoulder which indicates when 15 ml has been entered into thesyringe.

Finally, the two valves are retumed to the positions shown by solid lines in Fig. 1and the piston rod 17 of the first syringe 16 is pushed for moving all the remaining fluid (190ml) via valve 29 into the peritoneal cavity. The end result is that 4.5 gram of glucose or 15 mlof glucose solution has entered the peritoneal cavity after being diluted to below 3%. Inaddition, 75 ml of ultrafiltration fluid has been removed from the peritoneal cavity, resultingin a net UF of 60 ml.

As shown, the pistons of the second syringe 24 and the third syringe 25 will movesubstantially in unison if correct volumes are removed during use, because the diameters ofthe two syringes are correspondingly related. The gradings 31 and 32 at the syringes 24 and25 may be used for control.

The syringes 24 and 25 may be replaced by flexible bags, a glucose bag 25 initiallycomprising 300 ml of glucose concentrate at 30% and a UF bag 24 initially being empty andhaving a final volume of 1500 ml or larger. In this case it will not be possible to determine thevolumes of the bags during operation. However, the correct operation is assured by the gradings 33, 34 of the syringe 16.

The total Volume of the first syringe may be larger than 250 ml, since that onlyresults in that the glucose concentration in the fluid entered into the peritoneal cavity willlower than 3.0%. Thus, the syringe may have a volume of 250 ml, 260 ml, 270 ml, 280 ml,290 ml, 300 ml or larger.

Altematively, the removal of ultrafiltration fluid and the replenishment of glucosecan be made in two separate steps, whereby a smaller syringe can be used, having a Volume of190 ml or slightly larger as shown by broken line 35 in Fig. 1. In an ultrafiltration step, thefirst piston is pulled in order to fill the syringe with 190 ml of peritoneal fluid while the valvesare arranged as shown by solid lines in Fig. 1. Then, the first valve 29 is arranged as shown bybroken lines in Fig. 1 and the syringe is pushed according to arrow 19 until 75 ml of fluid hasbeen moved to the upper compartment 26 of the second syringe 24 and the first syringecomprises 115 ml. Now, the second valve is arranged as shown by broken lines in Fig. 1 and15 ml of glucose solution is entered into the syringe to a total volume of 130 ml by pulling thefirst syringe stem 17 as shown by arrow 18. Finally, the valves are arranged in the positionsshown in solid lines in Fig. 1, and the syringe is pulled until the end position to enter another60 ml of fluid into the syringe from the peritoneal cavity to a total amount of 190 ml, whichwill mix and dilute the glucose in the syringe to 3%. Finally, all solution inside the syringe isfilled back to the peritoneal cavity by pushing the syringe stem 17 to the end position to theleft in Fig. 1. It is desired to perform the UF step before the replenishment step.

The end result is that 4.5 gram of glucose or 15 ml of glucose solution has enteredthe peritoneal cavity after being diluted to below 3%. In addition 75 ml of ultrafiltration fluidhas been removed from the peritoneal cavity, resulting in a net UF of 60 ml.

The process is repeated each 30 minutes. Altematively, the process may beperformed more often, for example with intervals of 15 minutes or 20 minutes, or moreseldom, for example with intervals of 40 minutes or 45 minutes or 60 minutes.

The apparatus may also be used during the first fill as shown in Fig. 2, for example inthe moming. In this situation, the second syringe 24 is initially filled with 1500 ml of freshperitoneal fluid having a composition which is suitable for ultrafiltration, as discussed below.The peritoneal fluid in the second syringe lacks glucose. In addition, 345 ml of glucosesolution is provided in the glucose syringe. The syringes 24 and 25 may be replaced byflexible bags, as indicated above.

First, the first syringe 16 is operated to be filled with fresh peritoneal fluid (250 ml)from the second syringe 24 with the valves arranges as shown in Fig. 2. Then, the first valve29 is moved to the position shown in broken lines in Fig. 2 and the fluid is delivered to theperitoneal cavity by pushing the syringe rod 17 as shown by arrow 19. This process isrepeated two times, whereby the peritoneal cavity comprises 500 ml peritoneal fluid withoutglucose. Next, the first syringe is filled with only 235 ml of fluid from UF syringe 24, whereupon the second valve 20 is arranged in the position shown in broken lines in Fig 2 and 15 ml of glucose concentrate is entered into the first syringe 16. Finally, the first valve 29 isarranged in the position shown in broken lines in Fig. 2 and the contents of the syringe (250ml) is filled into the peritoneal cavity to deliver 4.5 gram of glucose to the peritoneal cavity.This is repeated three times. Now, there is 1500 ml of fluid in the peritoneal cavitycomprising 13.5 gram of glucose, which results in an initial glucose concentration of 0.9%.By this process, the peritoneal fluid initially entered into the peritoneal cavity during the firsttwo operation steps is void of glucose and the glucose concentration is increased stepwiseduring the next three operation steps until 09% concentration. Such a gentle introduction maybe advantageous for the peritoneal membrane.

The replenishment may be performed each 30 minutes. Infusion of 4.5 gram ofglucose per 30 minutes will compensate for the glucose absorption and possibly increase theintemal peritoneal glucose concentration until a balance is achieved, which may be larger orsmaller than 0.9%, depending on the patients characteristics for glucose absorption andlymphatic reabsorption etc.

If a start concentration of glucose other than 0.9% is desired, for example 1.0%, theglucose in the three last steps is increased correspondingly (18 ml glucose solution per step).

Removal of ultrafiltration fluid, for example 60 ml each 30 minutes will ensure thatthe peritoneal cavity pressure does not increase.

Finally, after completion of the treatment after for example 10 hours, the peritonealfluid inside the peritoneal cavity is drained into a drain bag. As shown in Fig. 2, a drain line27 is connected to a fourth inlet/outlet 28 of the first valve 29. The drain line 27 ends in adrain bag 30 having a volume, which is larger than the expected drain volume (1500 ml), forexample 2000 ml. By arranging the first valve 29 in the position shown by dotted lines andarranging the drain bag 30 at the floor, the peritoneal fluid will drain by gravity forces to thedrain bag 30. Finally, the complete apparatus is weighted, and the increase of weight is notedas the ultrafiltration obtained.

The fill step may altematively be performed by including the initial fresh peritonealfluid (1500 ml) in the fill/drain bag 30, including glucose in a desired concentration. Theinitial fill is done by arranging the first valve 29 in the position shown by dotted line andarranging the fill/drain bag 30 at an elevated position, whereby the fluid inside the fill/drainbag 30 is filled into the patient peritoneal cavity via gravity forces.

In another altemative, the initial fresh peritoneal fluid in the fill/drain bag 30 doesnot include any glucose. After filling the peritoneal cavity, several (three) replenishmentcycles are performed in order to increase the glucose concentration in a gentle manner. In thiscase, the UF syringe 24 should have a volume of 1500 ml plus 225 ml and the glucose syringeshould have a volume of 345 ml. It is mentioned, that the two syringes may be arranged witha larger volume and contents than indicated above, for allowing for operation during more than 10 hours, or for having a safety margin. 11 There are several parameters, which may be adjusted. Since the apparatus is arrangedto maintain the instilled fluid volume and the glucose concentration constant, the operationmay be assessed by measuring these values. If the volume finally drained into drain bag issmaller than the initially instilled volume of 1500 ml, the ultraf1ltration is too low. Thus, thereplenishment of glucose is increased the next day and vice versa.

Altematively, the fill/drain bag may comprise an excess of fluid, for example 2000ml or 2500 ml, and is arranged at an elevated position, which is about 20 cm above theperitoneal entrance position, while the patient is sitting or standing. Now, the fluid flows intothe peritoneal cavity until a balance is obtained, resulting in that the intemal peritonealpressure is about 20 cm water pillar (15 mmHg). Since the apparatus maintain the peritonealfluid volume substantially constant, the intraperitoneal pressure will be maintained at suchpressure.

It may be difficult to measure the volumes of the ultraf1ltration (75 ml) and theglucose solution (15 ml) at the gradings 33, 34 of the syringe and at the gradings 31 and 32 ofthe syringes 24 and 25. In an altemative design shown in Fig. 3, the syringes 24 and 25 areprovided with syringe stems 36 and 37, which move together with the pistons of the syringes.Each syringe stem is provided with screw windings (not shown). A nut 38, 39 is arranged tocooperate with each stem 36, 37 screw winding. By rotation of the nut 38, 39 or by rotation ofthe stem 36, 37, the height position of the nut may be adjusted along the syringe stem. Asshown in Fig. 3, the nut 38 of the ultrafiltration syringe 24 may be rotated to take a positionslightly above the bottom of the syringe. Thus, inflow of fluid into the syringe 24 is alloweduntil the nut 38 has moved down into contact with the bottom of the syringe, which preventsfurther inflow of fluid into the syringe 24. The same is true for the glucose syringe but in theopposite direction. An adjustment of the nut 39 upwards one step will allow removal ofglucose from the glucose syringe.

The adjustment may be arranged so that one revolution of the nut corresponds to 15ml of removed glucose solution and 75 ml of entered ultrafiltration fluid. If the syringes havea height of 10 cm, each revolution corresponds to 0.5 cm.

It is also possible to do replenishments at any time interval. If an interval of 15minutes is used, the nut is rotated half a revolution corresponding to 7.5 ml of glucosesolution and 37.5 ml of ultrafiltration.

The nuts may be adjusted separately or may be connected for simultaneous rotation.

The glucose replenishment and the ultrafiltration removal can be made independentlyfrom each other. For example, the replenishment of glucose can be made with intervals of 20minutes and the removal of ultrafiltration fluid can be made with intervals of 60 minutes.Such conditions are easily obtained by adjustrnent of the nuts 38, 39. This possibility reveals the patient from the responsibility of doing replenishments and UF removals at regular 12 intervals, but such actions can be done any time, although not too seldom. The gradings 31,32 will help the patient to maintain correct operation.

It may be more important to adjust the glucose concentration by replenishments moreoften than removal of UF fluid.

In another embodiment, shown in Fig. 4, the apparatus comprises a patient peritonealcavity 1, a catheter 2 and a connector 3. A patient connector 11 is connected to a patient line12, the other end of which is connected to a first inlet/outlet 52 of a valve 51. A secondinlet/outlet 53 of the valve 51 is connected to an ultrafiltration UF bag 55, which is flexible.

A third inlet/outlet 54 of the valve 51 is connected to a mixing chamber 56 andfurther to a first syringe 57 having a syringe stem 58. The third inlet is also connected via afirst one-way valve 61 to a second syringe 59 having a second syringe stem 60. The secondsyringe 59 is also, via a second one-way valve 62, connected to a glucose bag 72 comprisingglucose solution at a desired concentration, for example 30%.

The glucose bag has non-flexible extemal walls 71, so that the interior volume isconstant. The bag is divided in two compartments by a flexible partition wall 72. A firstcompartment comprises said glucose solution 73 and a second compartment 74 comprisesperitoneal fluid.

The operation is as follows: The syringe stems 58 and 60 are operated in unison by being interconnected by asyringe rod 75. In a first step, the syringes are filled with peritoneal fluid from the peritonealcavity 1 by pulling the syringe rod 75 according to arrow 76. The first syringe 57 is filled with175 ml of fluid and the second syringe 59 is filled with 15 ml of fluid. The sizes or diametersof the syringes are correspondingly dimensioned.

In a second step, the syringe rod 75 is pushed in the direction of arrow 77. Fluid inthe second syringe 59 cannot pass back the same way as it came, because the one-way valve61 blocks that path. Instead, the contents of the second syringe 59, via the second one-wayvalve 62, is entered into the second compartment 74 of the glucose bag 73. Because theglucose bag 73 is non-flexible, the entered volume displaces an equal volume of glucosesolution out via a line 78, which ends in an inlet/outlet 79 in the middle side of the mixingchamber 56. Simultaneously, the first syringe 57 passes peritoneal fluid through the mixingchamber and the fluid from the first syringe 57 is mixed with the fluid displaced from theglucose bag compartment 73 via the second syringe 59. The mixture is the same as the ratiobetween the two syringes, 175 ml and 15 ml, which results in a solution having approximately3% glucose concentration, which is entered into the peritoneal cavity. In addition, 15 ml ofperitoneal fluid has been maintained in the compartment 74 of the glucose bag.

Such glucose replenishments takes place at regular intervals, for example each 30 minutes. 13 It is noted, that the mixing Chamber 56 may be large or small, and even may be onlya connection of the line 78 to the line 89 connecting the syringe 57 with the first valve 51.

As mentioned above, the Volume of peritoneal fluid inside the peritoneal cavity willincrease over time. When it is desired to remove some ultrafiltration fluid, the process is thesame as above, with regard to the pulling of the syringe rod 75. However, before pushing thesyringe rod 75, the first valve 51 is switched to the position shown in broken lines, whichmeans that the fluid in syringe 57 and the glucose solution displaced by the second syringe 59now instead is directed to the UF bag 55. Now, 190 ml of peritoneal fluid has been removedto the UF bag. If an ultrafiltration of 2 ml/min is desired, the UF process is repeated each 95minutes.

In this process, glucose concentrate is passed to the UF bag 55, which may beregarded as a waist of glucose concentrate. However, glucose concentrate is inexpensive.

In an altemative method, the UF removal step is performed by making the syringestem 58 of the first syringe 57 free from the syringe rod 75 and operating the first syringe 57separately from the second syringe 59, which is maintained non-operated. Thus, 175 ml ofultrafiltration fluid is entered into the UF bag 55 without any extra glucose.

The replenishment step can be performed more often than each 30 minutes. Ifreplenishment is performed with 15 minutes intervals, the syringe rod 75 is only retractedhalfway, etc.

In the embodiment according to Fig. 4, the introduction of glucose, i.e. 15 ml, isbalanced by the removal of the same amount of peritoneal fluid, since the glucose bag 71 hasa constant volume. This gives a ratio of 1:1 for UF removal and glucose addition, resulting ina net UF removal of zero.

However, according to another embodiment, shown i Fig. 5, the ratio between the UFremoval and the glucose infusion may be larger and constant. One example is that eachinfusion of 15 ml (0.5 ml/min) of glucose solution is balanced by a net removal of 60 ml (2ml/min) of ultrafiltration fluid, or 75 ml (2.5 ml/min) if compensation for glucose infusion isincluded.

The apparatus according to Fig. 5 is similar to the apparatus according to Fig. 4.However, the second syringe 81 is larger and corresponds to a volume of 75 ml, while thefirst syringe 57 as before has a volume of 175 ml, or larger. In addition, the glucose bag isreplaced by a combined glucose bag and UF bag. The combined bag 82 is arranges as asyringe having circular cross-section. A piston 83 is arranged to be moveable along thesyringe 84. A bellow 85 is arranged to the left of the piston 83 and comprises glucose solutionat 30%. The bellow is surrounded by air, which is vented to the atmosphere. The diameter ofthe piston 83 is the square root of five, i.e. 2.24 times the diameter of the bellow. Peritonealfluid may be introduced to the right of the piston 83 via an inlet 86, resulting in that one fifthof the volume of UF fluid introduced to the right of the piston 83 is given off from the glucose 14 bellow 85 via Outlet 87. Thus, if 75 ml of UF fluid is introduced to the right of the piston, 15ml of glucose solution is given off via outlet 87. Outlet 87 is connected to the mixing chamberby means of a line 88 in order to mix with fluid from the first syringe as described inconnection with Fig. 4. The ratio between UF and glucose can be adjusted by changing thediameters of the bellow and syringe, while fine-tuning of the ratio is performed by adjustmentof the glucose concentration.

The piston 83 may include a grading as shown in Fig. 1 and/or a shoulder nut andpiston rod as shown in Fig. 3, see also Fig. 6. In this manner, the infused glucose solution andremoved UF may be controlled and monitored.

In the embodiment according to Fig. 5, no separate drain bag is required, except forthe final drain.

Fig. 6 shows a further embodiment of the invention. It is noted that the peritonealcavity always has a positive pressure, which may be 20 cm water pillar, or about 15 mmHg.This fact is used in the embodiment according to Fig. 6. The peritoneal cavity is connected tothe patient connector 11 and patent line 12 as described above. The patient line 12 isconnected to a flexible dilution bag 90 via a line 91 and to a combined glucose bag and UFbag 93 via a second line 92 and a restriction 94. Glucose solution is give off via a third line 99to the dilution bag 90.

The dilution bag 90 and the combined bag 93 are both arranged at a low position, ator below the exit of the peritoneal catheter from the peritoneal cavity. Because of thehydrostatic pressure and/or because of the positive pressure inside the peritoneal cavity,peritoneal fluid will exit from the peritoneal cavity into the dilution bag 90 until it is full. Thevolume of the dilution bag is 190 ml or slightly larger. In addition, peritoneal fluid will passto the upper compartment 95 delimited by a piston 96 of the combined bag 93 via a restriction94. The combined bag 93 and the restriction 94 are arranged so that the flow through therestriction is at least 2.5 ml/min, for example 5 ml/min. The down-ward movement of thepiston 96 is controlled by a syringe stem 97 and nut 98 as explained in connection with Fig. 3.

The operation is as follows: Peritoneal fluid is given off from the peritoneal cavity to the patient line 12 and flowsinto the dilution bag 90 by gravity flow. Such a flow may be about 50 ml/min which meansthat it takes about 4 minutes to fill the dilution bag 90, if it has a volume of 200 ml.Simultaneously, there is a restricted flow of 5 ml/min into upper compartment 95, whichresults in a glucose solution flow of 1 ml/min into the dilution bag 90. When 15 ml hasentered the dilution bag 90 after about 15 minutes, the flow stops because the nut 98 preventsfurther flow into the upper compartment 95. After another 15 minutes (totally 30 min), thepatient squeezes the dilution bag 90, resulting in an increased pressure in the dilution bag 90causing a flow of dilution fluid including 3% glucose to enter the peritoneal cavity. The fluid cannot flow from the dilution bag 90 to the upper compartment 95, since it is blocked by the nut 98 and stem 97. Fluid cannot escape back to the glucose bellow because of the hydrostaticratio resulting in a five-fold increase of pressure in the glucose bellow.

When all fluid has been squeezed to the peritoneal cavity, the nut 98 is screwed upone revolution, allowing the piston to move down until 75 ml of UF fluid has again beenentered in the upper compartment 95.

It is not important when the dilution bag is squeezed and how many times thedilution bag is squeezed during 30 minutes. Such squeezing can be done asynchronously. Inorder to ensure that the entered glucose concentration is below 3%, it is required that the fillrate of dilution bag 90 is more than about 12 times the fill rate of glucose. If the fill rate ofglucose is 1 ml/min, as mentioned above, the fill rate of dilution bag 90 by peritoneal fluid(0.7% or up to l.0%) should be at least about 14 ml/min (11.8 to 13.5) to yield a finalconcentration of less than 3%, which is norrnally achieved.

This method perforrns a more or less continuous removal of fluid from the peritonealcavity balancing the ultrafiltration. Simultaneously, glucose is replenished in a constant ratioin relation to the ultrafiltration. It is believed that such a balance is beneficial to the patient.

The apparatus according to Fig. 6 may be further improved by arranging a smallmotor at the nut, which rotates the screw by two revolutions per hour. In this manner, acontinuous and controlled removal of UF is obtained. The dilution bag 90 should besubstantially filled between each squeezing (which may take some 5 minutes), otherwise itcan be squeezed at any desired time.

The combination bag 93 may comprise a spring, which urges the piston 96downwards in order to ensure that a flow is obtained at all times, independently of the exactposition of the apparatus.

The dilution bag 90 may be of a bellow type similar to the glucose bellow and mayalso comprise a spring.

The apparatus may be modified for operation with a dual lumen catheter as shown inFig. 8.

The apparatus may be modified in many respects to make the operation more easy,which is greatly appreciated by patients, who often may have difficulties to operate theapparatus properly.

A further embodiment is shown in Fig. 7, wherein the manually operated valves arereplaced by one-way valves perrnitting flow in only one direction and blocking flow in theother direction. In addition, there is arranged a third syringe for ultrafiltration.

The apparatus 150, as shown in Fig. 2, comprises the patient line 12 connected viapatient connector 11 to the catheter connector 3 as in Fig. 1. The patient line 12 is connectedto a first inlet/outlet 152 of a mixing chamber 151.

The apparatus comprises three syringes, a glucose syringe 162 comprising a glucose syringe stem 163, a dilution syringe 164 comprising a dilution syringe stem 165 and an 16 ultrafiltration UF syringe 166 comprising an ultraf1ltration UF syringe stem 167. The dilutionsyringe 164 is connected to a second inlet/outlet 153 of the mixing chamber 151. The UFsyringe 166 is connected to the same second inlet/outlet 153 of the mixing chamber 151 via aone-way valve 168 which perrnits flow only in the direction towards the UF syringe 166. TheUF syringe 166 is also connected to an ultrafiltration UF bag 172 via a one-way valve 169perrnitting flow only from the syringe 166 to the UF bag 172. The UF bag 172 is alsoconnected to a fourth inlet/outlet 155 of the mixing chamber 151 via a tube comprising amanually operated clamp 173. The glucose syringe 162 is connected to a third inlet/outlet 154of the mixing chamber via a one-way valve 170 perrnitting flow only in the direction from theglucose syringe 162 to the mixing chamber 151. In addition, the glucose syringe 162 isconnected to a glucose bag 174 via a one-way valve 171 perrnitting flow only in the directionfrom the glucose bag 174 to the glucose syringe 162. The three syringe stems 163, 165 and167 are interconnected by a syringe rod 175 for movement in unison. The syringe stems canbe separated from the syringe rod 175 for separate movements.

The operation of the apparatus 150 is as follows: In a first step, the interconnection stem 175 is pulled to the right in Fig. 7, accordingto arrow 176. The glucose syringe 162 is filled with 15 ml of glucose solution. The dilutionsyringe 164 and the UF syringe 166 are filled with 175 ml and 75 ml of peritoneal fluid takenfrom the peritoneal cavity via the patient connector 11, patient tube 12 and mixing chamber15 1 .

When the syringe rod 175 has reached its end position, the direction of movement isreversed according to arrow 177. Now, the contents (75 ml) of UF syringe 166 is transferredto the UF bag 172 via one-way valve 169, since the one-way valve 168 blocks any otherroute. Simultaneously, the contents (15 ml) of the glucose syringe 162 is delivered to themixing chamber 151 via one-way valve 170 and inlet 154, which may be arranged in the sideof the mixing chamber as shown in Fig. 7, and the contents (175 ml) of the dilution syringe164 is delivered to the second inlet/outlet 153 of the mixing chamber, which may be arrangedat the end of the mixing chamber as shown in Fig. 7. Now, the flow of glucose via inlet 154 ismixed with the flow of peritoneal fluid via inlet 153 in a ratio deterrnined by the size of therespective syringes 62 and 64, which is 153175. Finally, the mixture of peritoneal fluid andglucose is delivered to the patient via the first inlet/outlet 152 of the mixing chamber. Theconcentration of glucose in said solution is less than but close to about 3%.

The glucose bag 174 may be provided with a grading indicating how much glucosehas been used similar to the embodiment shown in Fig. 1. If the treatment time is 10 hoursand replenishments are performed each 30 minutes, the grading or scale may have 20 lines. Inthis manner, the patient can determine that he has not missed any replenishment cycle by comparing the grading scale with the present time at his watch. 17 It is not necessary to make a full movement of the connection bar 175. Ifreplenishments are performed more often, for example after 15 minutes, only half of thevolumes are used. In this case, the connection bar 175 is pulled only half the way to the right.By reading the grading and comparing with the present time, the patient can determine theexact amount to use at any give time. For example, if the replenishment is performed after 20minutes, the patient pulls the connection bar 175 until the grading shows the correct amount.On the other hand, if the replenishment is performed after 40 minutes, a complete pulling ofthe connection rod 175 is not suff1cient for reaching the grading scale line corresponding tothe actual time. In this case, the patient first perforrns a complete pull followed by a completepush of the connection rod 175, where after the patient perforrns a non-complete second pulland push sequence so that the glucose indication becomes opposite the correct grading linecorresponding to the actual time. This, relieves the patient from performing replenishmentsexactly each 30 minutes, but the replenishments can be done more asynchronously, which isgreatly appreciated by the patient.

It is not necessary to do the ultraf1ltration removal and the glucose replenishmentsimultaneously. If an ultrafiltration sequence should be done separately, for example if thepatient deterrnines that the peritoneal fluid volume inside the peritoneal cavity is excessive,the UF syringe stem 167 is made free from the connection rod 175 and is operated separately.However, the glucose syringe 162 and the dilution syringe 164 are always operatedsimultaneously, at least during the push sequence, in order to assure that the infused glucosesolution has a concentration below 3%.

It is noted that if the UF bag 172 is arranged in a low position, peritoneal fluid maypass via the one-way valves 168 and 169 to the UF bag 172 in an uncontrolled manner. Inorder to avoid such unintended flow, the second one-way valve 169 may be arranged as apressure relieve valve as shown in Fig. 7, which allows flow only if the pressure exceeds apressure deterrnined by a spring 161 and prevents flow in the opposite direction. Suchpressure may be 100 mmHg, which is sufficient for preventing any undesired flow.

The above embodiments of the apparatus are arranged for being operated manuallyby the patient, whereby no battery is required since there is no device driven by a battery.Thus, the apparatus is very safe and easy to operate and is only dependent on the patient forcorrect operation. The apparatus comprises means which will aid the patient in correctoperation.

The apparatus is intended to be used during daytime, when the patient is awake formanual operation of the apparatus.

However, the apparatus is easily adaptable for night operation. The patient is anyhowimmobile in his bed during sleep in the night. Thus, there may be arranged electric devicesexerting forces on the syringe stems and electric devices switching the valves, in each of the different embodiments. 18 In the embodiment according to Fig. 7, an electric motor may be arranged to movethe syringe rod 175 according to arrows 176 and 177 as shown by broken lines. Altematively,a pneumatic or hydraulic actuator may move the syringe rod 175 according to arrows 176 and177, driven by a pneumatic or hydraulic power source.

In the embodiment according to Fig. 1, there is arranged an electric motor driving thesyringe stem according to arrows 18 and 19. In addition, there is arranged actuators, whichswitches the valves 12 and 20 appropriately. In the embodiment according to Fig. 3, there isadditionally two electric motors, which appropriately rotate the nuts 38, 39 or altematively thesyringe stems 36, 37. In the embodiment according to Fig. 5, there is only needed one electricactuator which drives the syringe stems in and out of the syringes. In the embodimentaccording to Fig. 6, there is needed an electric motor rotating the nut 98 and an actuatorsqueezing and releasing the bag 90 with regular intervals. Similar arrangements are made inthe other embodiments.

The electric motors and actuators may be arranged to be attached to the apparatus byreleasable devices, so that the apparatus may be put in a dock arrangement wherein theapparatus is connected to the motors and actuators for automatic operation and the apparatusmay be removed from the dock arrangement for manual operation.

If the patient wants to take a rest or siesta during daytime, the patient may arrangethe apparatus in the dock arrangement for automatic operation during the rest or siesta, andthen release the apparatus from the dock arrangement after the siesta for manual operation.

The apparatus may be arranged for operation in connection with a double lumencatheter. (Include some drawings) The apparatus should be provided with arrangements for priming. In the embodimentshown in Fig. 4, the drain bag 55 may initially be provided with 200 ml of priming solution.During a priming step, the valve 51 is arranged in the position shown in broken lines, and thepriming solution is delivered to the syringes 57, 59 by pulling the syringe rod 75 until 190 mlof fluid has been entered into the two syringes. Next, the syringe rod 75 is pushed wherebythe fluid in the second syringe 59 is passed to the glucose bag 71 and glucose concentrate ispassed via line 78 to the mixing chamber 56 and further back to the drain bag 55 together withthe contents of the first syringe 57. The priming step can be repeated several times.

Similar priming steps may be arranged in the other embodiments.

The patient having congestive heart failure may also have low blood pressure, whichmay compromise the operation of the kidney. The kidney may require support in removal ofexcess water, since the urine production is smaller than normal. However, the excretion ofmetabolic waste products, such as urea and creatinine, may norrnally be sufficient.

However, because of the low urine volume, an insufficient removal of sodium mayprevail. Thus, the fluid used in these embodiments may be modified by reducing the sodium concentration, which results in removal of sodium, in addition to removal of UF fluid as 19 described above. If the removal of potassium of the kidney is too low, a lowering of thepotassium concentration in the initial fresh peritoneal fluid may be appropriate, or evenelimination of potassium from the fluid. However, the body is sensitive to low potassiumconcentration in blood, and a lowering or removal of the potassium concentration should becarefully supervised by a doctor.

The patient having congestive heart failure may have a compromised blood pressureas indicated above. Such blood pressure may result in partial Withdrawal of capillaries in theperitoneal membrane and adjacent tissue, resulting in less exchange of substances between thefluid in the peritoneal cavity and the blood. The result is less ultraf1ltration. However, thecontinuous supply of glucose is expected to reduce any tendency for the capillaries towithdraw, since the body is not exposed to transient conditions. Thus, the gentle andcontinuous replenishment of glucose is expected to be of great importance for sensitivepatients.

The peritoneal membrane is sensitive to excessive exposure to glucose, which mayresult in peritoneal pain and peritonitis and tissue alterations. A gentle exposure of theperitoneal membrane to glucose may counteract such problems. Accordingly, the initialinstillation of fluid into the peritoneal cavity may take place with a low concentration ofglucose, or even zero glucose. Then, the concentration of glucose is increased slowly.

Due to the fact that a replenishment of glucose is made interrnittently with shortintervals, a low concentration of glucose may be used and still a desired ultrafiltration may beachieved. This is advantageous for avoiding pain and peritonitis as well for maintaining theultrafiltration function of the peritoneal membrane.

If the patient during the treatment is exposed to hypotension or other problems,resulting in withdrawal of capillaries in the peritoneal membrane, this is manifested as alowering of the ultrafiltration and a lowering of glucose absorption. The lowered glucoseabsorption may be monitored by a glucose sensor and may result in an alarm to the patientand/or supervising persons.

The glucose bag may comprise glucose at a concentration of 10%, 20%, 30%, 40%or 50 %. The volume of peritoneal fluid entered into the peritoneal cavity may be about 1 to 3liter, for example 1.5 liter. The peritoneal fluid may comprise ions of sodium 132 mM(mmole/liter), potassium 2 mM, calcium 2.5 mM, magnesium 0.5 mM, chloride 95 mM andlactate 40 mM. Lactate may be replaced by acetate or bicarbonate.

If sodium ions should be removed, the sodium ion concentration may be lowered to95 mM or lower. The potassium concentration may be lowered or removed.

The glucose bag may comprise some sodium or no sodium, in order to influence upon the sodium balance.

The osmotic agent mentioned above is glucose, Which has been shown to be WorkingWell for ultrafiltration of a peritoneal dialysis patient. However, other osmotic agents may beused such as Icodextrin, Which is a glucose polymer.

In the claims, the terrn "comprises/comprising" does not exclude the presence ofother elements or steps. Furtherrnore, although individually listed, a plurality of means,elements or method steps may be implemented by e. g. a single unit. Additionally, althoughindividual features may be included in different claims or embodiments, these may possiblyadvantageously be combined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. In addition, singular referencesdo not exclude a plurality. The terms "a", "an", “f1rst”, “second” etc. do not preclude aplurality. Reference signs in the claims are provided merely as a clarifying example and shallnot be construed as limiting the scope of the claims in any Way.

Although the present invention has been described above With reference to specificembodiment and experiments, it is not intended to be limited to the specific form set forthherein. Rather, the invention is limited only by the accompanying claims and, otherembodiments than those specified above are equally possible Within the scope of these appended claims.

Claims (7)

1. An apparatus for ultrafiltration of a patient in need thereof, for example a patientbeing overhydrated due to congestive heart failure, comprising: a patient line (12) comprising a patient connector (11) for connection to a peritonealcatheter connector (3) for access to a peritoneal cavity of the patient; a dilution receptacle (16) connected to the patient line (12) for removal and return ofperitoneal fluid to and from the peritoneal cavity; an ultrafiltration (UF) receptacle (24) arranged for removal of an ultrafiltrationvolume at regular time instances; a glucose receptacle (25) comprising glucose concentrate to be mixed with thecontents of the dilution receptacle (16) and subsequent introduction of the mixture into theperitoneal cavity; a metering device for metering an amount of glucose wherein the ratio between theUF removal and glucose infusion is constant at each time instance; whereby glucose is replenished intermittently for keeping a concentration of glucosesubstantially constant in the peritoneal cavity.

2. The apparatus according to claim 1, wherein the dilution receptacle is a syringe(16) having a retractable piston and a syringe stem (17) for operation of the piston, andwherein the apparatus further comprises: said UF receptacle (24); a first valve (29) and a second valve (20); wherein the first valve (29) is arranged for connection of the syringe (16) with said patientline (12) in a first position, and for connection of the syringe (16) with the second valve (20)in a second position; the second valve (20) is arranged for connection of the first valve (29) to the UFreceptacle (24) in a first position, and for connection of the first valve (29) to the glucosereceptacle (25) in a second position.

3. The apparatus according to claim l or 2, wherein the glucose receptacle and theUF receptacle are arranged as syringes (24, 25) each comprising a syringe stem (36, 37)attached to a corresponding piston and a nut (38, 39) arranged moveable along the syringestem for limiting the movements of the pistons inside each syringe.

4. The apparatus according to claim 1, wherein the dilution receptacle is a firstsyringe (57) having a piston and a syringe stem (5 8) for operation of the piston, and whereinthe apparatus further comprises a second syringe (59) having a retractable piston and asyringe stem (59) for operation of the piston, and 2 Wherein the glucose bag comprises an enclosure (71) having a constant volume, anda partition wall (72) dividing the enclosure into two compartments, a first of which (73)comprising said glucose concentrate and a second of which (74) comprising at least a portionof said ultrafiltration volume, and Wherein introduction of peritoneal fluid inside the secondcompa1tment(74) displaces an equal volume of glucose concentrate out of the firstcompartment (73).

5. The apparatus according to claim 1, wherein the dilution receptacle comprises adilution syringe (5 7) having a piston operated by a syringe stem (58) and being connected tothe patient line (l2); and further comprising an ultrafiltration syringe (81) having a piston anda syringe stem and being connected to the patient line (12) via a one-way valve (61) andfurther being connected to a combination bag (82) via a second one-way valve (62), Whereinsaid combination bag comprises a first compartment for ultrafiltration fluid and a secondcompartment (84) comprising glucose concentrate, whereby inflow of ultrafiltration fluid insaid first compartment results in an outflow of glucose concentrate, wherein the ratio betweeninflow and outflow is constant and larger than one, for example 5:1.

6. The apparatus according to any one of the previous claims, Wherein said regulartime instances are at time intervals of between 15 minutes and 60 minutes, such as about 30minutes.

7. The apparatus according to any one of the previous claims, Wherein said ratio isdetermined separately for each patient.